Various methods have been employed in the prior art to disperse and restrict the flow of liquids and solids. “Butterfly” type valves are known including those of the following U.S. Pat. No. 5,246,032 to Muddiman, U.S. Pat. No. 4,076,035 to Frisch, U.S. Pat. No. 3,559,679 to Smirra, U.S. Pat. No. 6,012,483 to Beddies and U.S. Pat. No. 5,711,343 to Beckett. All of these patents teach flow restriction of matter in manners which are different from the present invention.
Specifically related to particulate food matter are a number of devices implemented in dispensing bulk material. Vertical form/fill/seal (“VFFS”) machinery is one of the most efficient manners to package bulk material into individual flexible packages, such as cake mix bags.
In a VFFS machine, bulk material (such as powdered cake mix) is typically directed from a feed hopper, through a flow tube and flow tube outlet and into a package. A rotatable auger may be located in the flow tube to urge the bulk material toward the outlet.
Typical VFFS machinery includes the use of heat-sealed film formed into bag-type packages used to contain the bulk material. The film is provided in the form of a web wound on a supply roll. The web is unrolled from the supply roll and passes over rollers which control web tension and re-direct the web into a generally vertical orientation. The web is wrapped over a vertical hollow cylindrical mandrel called a forming tube. The forming tube is located over, and concentric with, the flow tube. A set of horizontal jaws closes each filled package transversely performing three packaging functions nearly simultaneously: (1) the upper seal of a filled package is heat sealed; (2) the lower seal of the empty upper package (i.e., the next sequential package) is heat sealed; and (3) the lower filled and sealed package is separated from the web as a discrete package by a transverse knife which cuts between the two seals. The bulk material product is discharged from the filler and into the open upper end of the package just above the transverse sealing jaws. The jaws open and the filled package is advanced (lowered) so that what was the package above the jaws becomes the package below the jaws. The cycle repeats.
One problem facing the operator of the bulk-material metering machine is to control the flow of the bulk material from the bulk-material metering machine and into the package. Complicating this problem is the fact that many bulk material metering machines, such as VFFS machines, are designed to perform in excess of 100 dispense cycles per minute. If provided, the rotating auger urges the bulk material through the flow tube. The metering or portioning of the bulk material occurs as a result of starting and stopping the auger. Depending on the flow characteristics of the material being filled, the material may not stop flowing when the auger stops turning, resulting in uncontrolled discharge of the bulk material.
One undesirable manifestation of this uncontrolled bulk-material flow is a condition referred to as bulk material “drip.” Drip can occur, for example, when loading powdered cake mix into a package utilizing a bulk-material metering machine. The continual flow, or drip, of bulk material is a problem because the falling material can interfere with the package sealing process by falling onto the package portion being sealed, thereby possibly interfering with seal formation. Formation of an incomplete seal is undesirable because the packaged product can become spoiled and rendered unsalable.
A number of strategies have been proposed to control bulk material flow and to limit or stop the occurrence of bulk material “drip.” Each of these strategies has certain disadvantages.
One strategy includes the use of a “cut-off” device to positively stop the flow of bulk material from the flow tube outlet. A number of such devices are known. One such device is a slide gate powder cut-off device used with VFFS machinery and sold by Mateer-Burt, Inc. This gate device is located at least partially between the flow tube and forming tube. The forming tube must have a diameter large enough to accommodate the gate assembly.
One possible concern with this device is that its use of a sliding gate may cause cleanliness problems associated with the use of sliding joints in a contaminated area.
A more serious disadvantage is that the slide gate makes the bulk-metering machine less efficient. This decrease in efficiency results from the fact that the machine throughput is relatively decreased given the larger packaging volumes required by the proportionally larger forming tube required to accommodate the gate assembly. Generally, it is most desirable to size the flow tube as closely as possible to the forming tube so that a smaller package can be used and so that less work is required to fill the package unit volume. Put another way, use of an auger which is proportionally larger relative to the package to be filled makes the filling process more efficient and boosts throughput because relatively fewer turns of the auger are required to fill the package. The bulk of the slide gate and the larger size of the forming tube required to accommodate the slide gate causes the bulk-material metering machine including such a cut-off device to be relatively less efficient.
Another known apparatus is a horizontal gate, or drip tray, sold by All Fill, Inc. This gate device utilizes a tray located to the side of the material outlet and which is extended under the outlet from the side location. This device is not optimal for use with VFFS-type bulk material metering machinery because, once again, a larger forming tube is required to accommodate the side-mounted tray.
Yet another known cut-off device, and a device most commonly used in VFFS machinery, is a double flapper cut-off assembly manufactured by Auger Manufacturing Specialists, Inc. However, this device is not optimal because the rectangular shape of the double flapper and the cylindrical shape of the bulk material flow tube once again require a larger forming tube, making the machine relatively less efficient and wasting valuable space.
In an effort to overcome this problem, the size of the parts comprising the hinges and flapper mechanism have been reduced thereby permitting use of a smaller forming tube. However, this is disadvantageous because using less robust parts can increase the likelihood of flapper assembly failure, reducing machine service life and decreasing machine efficiency. More robust double flapper assemblies are made at the expense of flow area, ultimately reducing efficiency and product output.
Another strategy used to combat bulk material “drip” is to slow the rate at which the bulk-material metering machine operates. This can be accomplished by providing a greater time duration between termination of auger rotation and sealing of the package. Since most of the drip occurs immediately after termination of auger rotation, delaying initiation of the sealing operation should minimize or avoid drip-based interference with the sealing operation. Unfortunately, this strategy greatly reduces bulk-material metering machine efficiency and is contrary to the objective of increasing throughput.
Efficient operation of the bulk metering machinery is of utmost importance to the manufacturing facility operator. The operator must continuously seek to achieve the same or greater amounts of packaging throughput with the least number of bulk material filling machines. Filling lines utilizing machines, such as VFFS machines, come at great expense, costing typically around $100,000. Manufacturing facility floor space is valuable and must be utilized in the most efficient manner possible. Extending the duration of the dispense cycle is simply not an acceptable strategy for filling lines with potentially high throughput, for instance 7000 packages per hour.
It would be an improvement in the art to provide an improved apparatus for controlling the flow of bulk material discharged from a bulk-material metering machine, which would facilitate efficient, improved operation of the bulk-material metering machine and which would provide for improved packaging of the bulk material metered out from the machine.